[rú zuò zhēn zhān]
sit on pins and needles; as if sitting on a spiked rug; be in an extremely uncomfortable position; be kept on the anxious seat; be on nettles; be on tenterhooks; be [sit; stand; walk] upon [on] thorns; feel as if sitting on a bed of nails; feel extremely uneasy; like a cat on hot bricks; sit on a cushion of needles -- ill at ease; sit on thorns; sitting on a rug [a carpet] full of needles